In typical machining operations, coolant must be supplied to machine sections during machining of parts to cool the sections and flush waste such as particulate away. Without coolant, tools in the sections would quickly break down and become dull from overheating or from a build up of waste. The sections output dirty coolant containing the particulate into a flume. The flume is generally disposed underneath the sections so that the dirty coolant falls into the flume. The flume typically has a slope and an outlet end connected to a filtration apparatus or sump so that the dirty coolant flowing within the flume flows to the filtration apparatus. The filtration apparatus cleans the dirty coolant by filtering out the particulate which is then discarded or recycled. A pump then pumps clean coolant from the filtration apparatus to the sections and the coolant recirculation process continues.
Problems with the coolant recirculation process surface when the particulate builds up in the flume. For steady state operation the particulate needs to be removed from the flume at a rate faster than it builds up or else, at some point, the coolant in the flume overflows. Build up of particulate in the flume may be caused by inadequate flow velocity of the coolant flowing within the flume. For instance, if the particulate is iron, which has a relatively large specific gravity, then a higher flow velocity is required to wash it away. In contrast, if the particulate is aluminum, which has a relatively low specific gravity, then a lower flow velocity is required to wash it away.
In a typical system, many sections are grouped together and the flume can become very long. A flume length of 200 to 400 feet is common. These flumes, as a result of their slope, become as deep as six to twelve feet. Consequently, the flumes must be cut into the floor supporting the sections to properly fit underneath the sections. Usually, the floor is made of concrete and the flumes are embedded therein.
A flume system having a below floor mounted flume as described above presents many disadvantages. First, it is expensive to dig and excavate. Second, the filtration apparatus is installed underground in a pit which is very costly. Another approach is for a pump to pump the dirty coolant from the outlet end of the flume up to an above ground filtration apparatus. This is disadvantageous because the pump pumps both coolant and particulate. The particulate can plug or result in accelerated wear to the pump. Thus, expensive vortexing type or self-priming trash pumps are needed. These pumps are extremely inefficient having an efficiency in the range of 50% to 60%. The pumps also require that maintenance be performed frequently due to pumping of the particulate.
Above floor mounted conveyorized troughs have been installed within sections. Conveyors rest on the bottom of the trough and push particulate towards the filtration apparatus. A disadvantage with conveyors is that they obstruct the flow of coolant in the trough and, consequently, the coolant can back up and flood the floor. Additional trash pumps have been installed part way down the length of the trough to overcome this problem. Conveyors are also high maintenance and difficult to service under the sections. To keep the coolant from splashing out of the trough and to keep the mist down, the sections and the trough are covered. Consequently, the conveyors are inaccessible.